Abstract The proposed project will complete the development of and evaluate the efficacy of Master Mind, a mindfulness education substance abuse prevention for late elementary school-aged children. Past research has found that mindfulness has many benefits for youth, such as increases in attention, social competence, and emotion regulation, as well as decreases in stress, sleep problems, depression, anxiety, and externalizing behaviors. Training in mindfulness may provide children with new ways to cope with stress and make healthy decisions in a variety of situations, thereby preventing children from turning to alcohol or tobacco to solve their problems. None of the existing substance abuse prevention curricula include any mindfulness training or application of mindfulness skills to children's everyday lives. The Master Mind program is designed to address these critical gaps in the content of contemporary prevention programming through providing developmentally appropriate, contemplative education practices. Hence, the development and marketing of an empirically- validated, mindfulness education, substance abuse prevention program for elementary school students can provide teachers, school administrators, and prevention specialists with a currently unavailable resource. In Master Mind, children participate in activities focused on the foundations of mindfulness (e.g., awareness of thoughts) including mindful movements, mindful breathing, and mindful journeys, and most importantly, learn how to apply the mindfulness skills to their everyday lives. In Phase II of this project, the four-week Master Mind program will be completed with input from experts in mindfulness, yoga, children's self- regulation, instructional design, and implementation fidelity, as well as with input from elementary school teachers and students. In the first year of this project, elementary school students will participate in focus groups to preview the lessons and provide feedback on the mindfulness activities. Following this, a pilot study of the revised program will be conducted two elementary school classrooms (one 4th and one 5th) to observe the implementation of the revised Master Mind program and pilot the entire data collection protocol with teachers and students. In year two of the project, we will conduct a randomized controlled trial (20 intervention classrooms and 20 wait-list control classrooms) of the effectiveness of the Master Mind program for improving children's self-regulatory abilities and in turn, reducing their intentions to use and actual use of alcohol or tobacco.